Electric switch



Nov. 22, 1932. J, w s 1,888,559

ELECTRIC SWITGH Filed April 30, 1930 6 Sheets-Sheet 1 INSULATIONINSULATION gwumtoc Jail/11s Nov. 22, 1932.

M. J. LEWIS ELECTRIC SWITCH Filed April 30, 1930 6 Sheets-Sheet 2 47 440 56 :5; 55 6l 62 do Nov. 22, 1932. M. .1. LEWIS ELECTRIC SWITCH FiledApril 50. 1930 INSULATION INSULATION 6 Sheets-Sheet 4 gwueml ov MJbelwls I 8% www M. J. LEWIS ELECTRIC SWITCH Nov. 22, 1932.

Filed April 50. 1950 e Sheets-Sheet 5 gwmmto'o MJAe Nov. 22, 1932.

Filed April 30. 1930 6 Sheets-Sheet 6 INSULATION INSULATION gwmnio'oPatented Nov. 92, 1932 UNITED STATES MORGAN J. LEWIS, OF MASSILLON, OHIOmadame swrrcn Application filed a 'i-u 80, 1930. Serial No. 448,593.

The invention relates to electric switches and particularly to a Switchwhich will automatically open a circuit immediately upon the occurrenceof an abnormal overload and 6 after a brief lag upon the maintenance ofa slight overload.

It is known that automatic circuit breakers have been made in the past,but such circuit breakers have been provided with a brush 10 type ofcontacts, which are objectionable because of a speck of dirt or thelike, or a slight projection upon the face of one of the contacts,caused by arcing or the like, frequently prevents a positive contactfrom being made.

The object of the improvement is to overcome the objections anddifiiculties encoun tered in such devices, by providing an automaticswitch having blades receivable within contact jaws whereby a positivecontact is assured when the switch is closed.

Another object of the improvement is to provide a switch of thischaracter in which a latch is provided for normally holding the switchblades in closed position, a spring pressed device being provided forreleasing the latch, means being provided for immediately operating said5 ring ressed device upon the occurrence 0 an a normal overload and foractuating the spring pressed device after abrief lag upon the occurrenceof a slight overload.

The above and other objects may be attained by providing a hook-shapedlatch for normally holding the switch blades in closed position, aspring operated device being operatively associated with said latch andnormally held in' the inoperative position by means of a hookedthermostatic bar formed of laminated strips of metals welded orotherwise fastened together and having different coeflicients ofexpansion, a magnet coil being located adjacent to the thermostatic barfor attracting the same.

A toggle link device may be connected to the switch blades andoperatively associated with the operating handle and adapted to bebroken bythe operation of said spring pressed device.

An embodiment of the invention is illus-' ing the same in position to beclosed by the switch handle;

Fig. 7, a section on the line 7-7, Fig. 1; Fig. 8, a longitudinalsection showing the iwitfii in the act of being opened by the an e;

Fig. 9, a plan section of the latch mechanism;

Fig. 10, a detail perspective view of the thermostatic device;

Fig. 11, a side elevation of a modified form of the invention for useupon switchboards and the like.

Fig. 12, a plan view of a switch provided with three blades;

Fig. 13, a side elevation of the same; and

Fig. 14, a plan section of the latch mecha nism of the three bladeswitch shown in Figs. 12 and 13.

Similar numerals refer to similar parts throughout the drawings. Theimproved switch mechanism to which the invention pertains may be mountedu on an insulation block 12 located within a switch box of any usual andwell known construction, as shown generally at 13. The invention isapplicable to switches having one, two, three or four blades, and forthe purpose of illustration it is shown in Fi 1 to 10 inclusive asapplied to a switch having two blades.

A pair of pivot contacts 14 are fixed upon the insulation block spacedfrom each other and located near one end of the block to which arepivoted, as at 15, the switch blades 16 connected to the insulationcrosspiece 17 at points spaced from their free ends which are adapted toengage the contact jaws 18 mounted upon the insulation block 12 near theother edge'thereot and having connected thereto the terminals 19.

A bracket 20 may be fixed upon the insulation block 12 adjacent to eachof the pivot contacts 14 and carries a magnet coil 21, one

wire, as indicated at 22, being connected to the adjacent terminal 23,fixed upon the insulation block 12 at a point spaced from thecorresponding pivot contact 14.

An angle bracket 24 is fixed upon each pivot contact 14 and the lowerend of one arm 25 of a U-shaped thermostatic device is connected to saidangle bracket as by a screw 26,

theother arm 27 of the thermostatic device being connected, at its lowerend, to an angle bracket 28, as by the screw 29.

The bracket 28 is fixed upon the insulation block 12 as by the screw 30and nut 31, to

-which is also attached the other wire 32 'leading to the adjacentmagnet coil 21;

The thermostatic device'referred to may be formed of two layers of metalwelded or otherwise fastened together and having difrent flows throughthe arms 25 and 27 for relatively short time, the layers of metalscomprising the arms will expand ditleren tially, due to their diflerentcoeihcients of expansion, and the arms will bend outwardly toward theadjacent magnet 21.

' A frame is mounted longitudinally upon the central portion of theinsulation block 12 and is formed of the spaced side members 35 whichmay have their upper portions connected as by the crosspiece 36 on theend of the frame adjacent to the thermostatic devices.

The latch mechanism is located in the opposite end portion of this frameand may be in the. form of the hook 37 pivoted at its lower end betweenthe side members of the frame, as at 38, and provided with a spring v39for normally urging the upper hooked end 40 thereof inward to hold theswitch blades in closed position, as will be later described.

The latch releasing mechanism may include the releasing plates 41, oneend of each late being pivoted upon the pin 38, the ot er end having theupwardly disposed and outwardly inclined arm 42 arranged to benormallyengaged under the hook 34 of the adjacent thermostatic device.

A coil spring 43' is connected to the adja- 56 being carried cent endportion of each releasing plate 41 and to the upper portion of the frame35 for normally urging each of the releasing plates into the positionshown in Fig. 4, so that the arm 44, upon the opposite end thereof-Lwill tend to move the latch 37 intothe releasing position.

A coil spring 45 may be fixed upon the insulation block and adapted tobe compressed by contact with the insulation crossbar 17 of the switchwhen the blades are in the closed position and tending to throw theblades out of engagement with the contact jaws 18 when the latch isreleased.

For the purpose of quickly throwing the switch blades to the fullyopened position, as .shown in Fig. 5, a pull spring 46 may be connectedat one end to the insulation cross bar 17, the other end being connectedto the opposite end portion of the frame 35-.

For the purpose of manually closing the switch and also for manuallyopening the same when desired, a switch operating handle may be providedinthe form of a crankshaft 47, of a design which is usual and well knownin switch boxconstruction and which. may be journaled through oppositeside walls of the box 13 and provided upon" one end with the handleportion 48 located upon the exterior of the box.

A toggle link construction may be provided between the switch handle andthe insulation cross bar 17 and comprising the link 49, preterably ofchannel cross sectional shape and having the pivot pin 50 locatedthrough the elongated slot 51 in the bracket 52, which is fixed upon theupper side of the insulation cross bar 17, as by the screw 53.

The link 54 may also be of channel cross sectional shape and ispivotally connected to the link 49 as by the pin 55, the spring by saidpin and having its opposite ends engaging the under sides 0 the links 49and 54 and tending to urge them into alinement with each other, as shownin Figs. 3 and 6, with the inner end 57 of the link 54 butting againstthe shoulder 58 of the link 49.

The outer end of the link 54 has the elongated slot 59 which receivesthe crank portion 60 of the switch operatinglever. As best shown inFigs. 3 and 6, the pivotal point 55, between the links 49 and 54, isbelow a straight line passing through the centers of the ivotal points50 and 60.

. ith the switch in the closed position, as shown in Figs. 1, 2 and 3,the crank portion 60 of the operating handle is at the lighter inner endof the elongated slot 59 in the link 54, the links 49 and 54 beinglocated in alinement with each other and the central upright leg 61 ofeach releasing plate contacting at its up er end with the pivot pin 55of the tog le lin rs.

-The hoo 40 of the latch is engaged over' the iii) pin 50, preventingthe switch blades from being withdrawn from the contact jaws. Assumingthere is a sudden heavy overload in the circuit, one or the other of themagnet coils 21 will immediately attract the cross bar 33 of thecorresponding thermostatic device, pulling the hook 34 out of engagementwith the upturned arm 42 of the corresponding releasing plate, thespring 43 thereof immediately pullin the releasing plate into theposition shown in Fig. 4, the upright central leg 61 of the platethrowing the pivotal connection between the toggle links upward,breaking the joint as shown in said figure.

Atthe same time the inner end of the re= leasing plate will force thelatch book 37 outward, releasing the same from engagement with the pin50 ot the switch. The compressed spring-45 will immediately force theswitch blades upward out of engagement with the contact jaws and thespring 46 will continue to move the switch blades to the fully openedposition, as shown in 5.

As the insulation cross bar 17 engages the central upright leg 61 of thereleasing plate it will push the same back and down to the normalposition, moving the arm 42 at the end thereof back beneath the book 34of the thermostatic device, while the insulation cross bar 17 comes tovrest within the notch 62 in the leg 61.

Uh the other hand, if a slight sustained overload of current occurs inthe circuit, which overload is not sufficient to energize v the magnets21, after a brief pause the layers metal in the thermostat? c memberswill by differential expansion bend to release the hooks 34, and thecooperating parts will immediately function to open the switch in themanner above described.

.ln order to close the swit h from the position shown in Fig. 5, thehandle 47 is first swung counterclockwise to bring the links 49 and 54into straight line position as shown in Fig. 6 with the pivot below deadcenter. Upon then swinging the handle in the opposite or clockwisedirection, the switch blades are forced into engagement with the contactjaws 18 against the action of springs 46 and 45 when the hook 40 willengage the pin 50 to hold the blades in closed position.

llf it is desired to manually open the switch, assuming the parts to bein closed position as shown in Figs. 1, 2 and 3, the handle 47 is movedcounter-clockwise as viewed in said figures. During the initial art ofthis movement, the portion of t e handle travels from the right end ofthe slot 59 of link 54 to the left end of the slot rotating the link54about the pivot 55, which is supported on the leg 61 of the releasingplate, and breaking the joint between the links as shown in Fig. 8. Atthis point further counter-clock wise rotation of the handle will, byengagementof the portion 60 with the left end of the slot, move bothlinks 49 and 54 to the left until the pin 50 is released from engagementwith the hook 40 of the latch 37, When the springs 45 will throw theswitch blades out of the contact jaws and the springs 46 will pull theswitch blades to fully open position.

In Figs. 12 to 14 inclusive the invention is illustrated as applied to athree blade switch, otherwise similar to the switch shown in Figs. 1 to10 inclusive. In this form of the invention the switch mechanism may bemounted upon the insulation block 12s, the pivot contacts 14a and 14bbeing fired thereon in spaced relation and having pivoted thereto theswitch blades 16a and 166, .all of which are connected near their freeends to the insulation cross bar 17a.

The free ends of the blades 16a and 166 are adapted to engage thecontact jaws 18a and 187) respectively, which are fixed upon theinsulation block 12a near the opposite edge thereof and having connectedthereto the terminals 19a and 197) respectively.

The brackets 20a and 20?) are mounted upon the block 12a, the brackets520a being preferably located adjacent to the pivot contacts 14a and thebracket 20?) preferably near the adjacent edge of the insulation block,a point between the brackets 20a. 'lhese brackets carry the magnet coils21a and 216 respectively connected at one side to the terminals 23a 23b.

The other side of each coil 21a is connected to the corresponding pivotcontact 14a through the bracket 24a and the other side of the coil 215is connected to the pivot contact 141) as through the bus bar 524?).

A thermostatic device, similar to that described above in the two bladeswitch illustrated in Figs; 1 to 10 inclusive, is associated with eachof the magnet coils, these thermostatic devices being illustratedgenerally at 250. and 25b.

The frame 35a. is mounted longitudinally upon the central portion of theinsulation block and houses the latch and releasing mechanism whichincludes the latch hook 374; similar to the hook 37 above described.

The releasing mechanism includes three releasin plates similar to theplates 41 above descri ed, the central plate 41?; cooperating with thethermostatic device 256 and magnet coil 21?) while the two outer plates41a cooperate with the thermostatic device 25a and magnet coils 21a inthe manner above described pertaining to Figs. 1 to 10 inclusive. Y

The'remainder of the switch illustrated in Figs. 12 and 13 is of thesame construction as above described and illustrated in Figs. 1 to 10inclusive, and the operation of the switch is the same as abovedescribed, a sudden heavy overload energizing either of the magnets 21sor 216 to immediately throw out the switch, while a sustained slightoverload will operate any one of the thermostatic devices 25a or 25?) tothrow out the switch after a brief pause.

In Fig. 11 is. shown an adaptation oi the invention to a switchadaptable for use upon switchhoards and the like, in which the mechanismis mounted upon the insulation block 120, the switch blades 160 beingpivoted upon the pivot contacts l lo and their free ends adapted to engae the contact jaws 18c.

A magnet coi is mounted upon a bracket 20c adjacent to each pivotcontact and associated with a thermostatic device such as abovedescribed and illustrated in Fig. 10 and adapted to cooperate with thecorresponding releasing plate ila, housed. within the frame 350, in themanner above described.

The releasing plate cooperates "with the latch hook 37 as abovedescribed, this hook engaging the pin 500 in the bracket upon theinsulation crosspiece 170, all as illustrated in Figs. 1 toll) and abovedescribed.

The operating handle may be in the form of a segment 65, pivoted as at'86 upon the frame 350 and provided with a knob 67 for operating thesame. The links 490 and 540 are pivotally connected together as by thepin 550 and are similar to the links 49 and 54 above described andillustrated in Figs. 1 to in clusive, the link 490 being pivoted to the.bracket 520 by the pin 50c, and the link 540 having the elongated slot590 which receives the pin 600 carried by the segment 65.

In-the closed pos tion of this switch, the

pivotal point 550 is below a line drawn through the centers c and 500and contacts with the upright linger 610 of the releasing plate 410.With the exception of the handle arrangement, the operation of theswitch is the same as above described.

I claim:

1. An electric switch, a latch. for normally holding the switch inclosed position, a spring operated releasing plate for releasing thelatch, means for automatically opening the switch when the latch isreleased, a thermostatic device-in circuit with the switch for normallyholdin the releasing plate inoperas tive and for re casing saidreleasing plate after a. brief lag upon the maintenance of a slightoverload, and a magnet coil in circuit with the switch for attractingsaid thermostatic device to release the releasing plate immediately uponan abnormal overload:

2. An electric switch,a handle for manual- 1y operatinglthe switch,links connecting said switch and andle and having a pivotal connectionwith each other forming a joint, a latch for normally holding the switchin closed position, means engaging the pivotal connection between thelinks for automatically breaking the joint of the links and opening theswitch when the latch is released, and a thermostatic device in circuitwith the switch for releasing said latch.

3. An electric switch, a handle for manualnssatee ly operating theswitch, links connecting said switch and handle and forming a joint, a.latch for normally holding the switch in closed position, meansoperating independentlyof the handle for automatically breaking thejoint of the links and opening the switch when the latch is released,and a magnet coil in circuit with the switch for releasing said latch.

An electric switch, a handle for manually operating the switch, linksconnecting said switch and handle and having a pivotal connection witheach other forming a ioint a latch for normally holding the switch inclosed position, means engaging the pivotal connection between the linksfor automatically breaking the joint of the links and opening the switchwhen the latch is released, and a thermostatic device in circuit withthe switch for releasing said latch after a hriei lag upon themaintenance of a slight overload.

5. An electric switch, a handle for manually operating the switch, linksconnecting said switch and handle and having a pivotal connection witheach other forming a joint, a latch for normally holding the switch inclosed position, means en aging thepivotal connection between the lin sfor automatically breaking. the joint of the links and opening theswitch when the latch is released, a

thermostatic device in circuit with the switch for releasing said latchafter a brief lag upon the maintenance of a slight overload, and amagnet coil for operating said thermostatic devce immediately upon anabnormal overloa 6. An electric switch, a handle for manually operatingthe switch, links connecting said switch and handle and forming a joint,a

latch for normally holding the switch in closed position, a springoperated releasing plate for releasing the latch and breaking theiointof thelinks, means for automatically opening the switch when the latchis release and a thermostatic device in circuit with the switch fornormally holding the releasing plate inoperative.

"7. An electric switch, a handle for manual ly operating the switch,links connecting said switch and handle and forming a joint, a latch fornormally holding the switch in closed position, a spring operatedreleasing plate for releasing the latch for braking the'joint of thelinks, means for automatically opening the switch whenthe latch isreleased, an armature for normally holding the releasing plateinoperative, and a magnet coil in circuit with the switch ior attractingsaid armature immediately upon the occurrence of an abnormal overload. V

8. .An electric switch, a handle for manual- 1y operating the switch,links connecting said switch and handle and forming a joint, a. latchfor normally holding theswitch in closed position, a spring operatedreleasing MORGAN J. LEWIS.

